Over the past decade, the number of people living with HIV has increased while the annual number of new infections has remained relatively stable. Gay, bisexual, and other men who have sex with men (MSM), particularly young black/African American MSM (YBMSM), are disproportionately impacted. The number of new cases among people aged 13-29 years increased by 21% from 2006 to 2009, fueled by a 34% increase in HIV infections among young gay and bisexual men. Although MSM represented about 7% of the male population in the United States in 2010, MSM accounted for 78% of new HIV infections among males and 63% of all new infections. Innovation: Smartphone mobile apps present innovative opportunities for discreet, targeted outreach to young MSM (YMSM). HIV care, prevention, and health maintenance interventions, which can be delivered to the subject or their care partner through smartphone apps, have the potential to increase HIV testing, facilitate immediate linkage to appropriate HIV services, encourage early access to treatment, and support sustained health maintenance measures. Preliminary Data: Recent studies explore the use of technology to promote healthy behaviors in various populations. There are several studies that explore the use of technology for MSM. Specifically, a study by Holloway et al (2013) demonstrates promising findings on the acceptability of smartphone application-based HIV prevention among YMSM. Hypothesis: We hypothesize that YMSM in an urban setting: 1) currently utilize smartphone technology and will do so for HIV prevention and health maintenance; 2) will accept and utilize a novel HIV-specific smartphone app for prevention and disease management.; 3) the integration of a smartphone app-based technology will be an effective mechanism to address HIV care and prevention in this population. Specific Aims: Phase I will investigate the feasibility and acceptance of a smartphone app for HIV care and prevention, in collaboration with researchers at Joint AIDS Community Quest for Unique and Effective Treatment Strategies (JACQUES) Initiative of the Institute of Human Virology (IHV) at the University of Maryland School of Medicine (JI) in Baltimore. In Specific Aim 1, we will assess the current smartphone use and willingness of a representative population to use a proposed smartphone app for HIV care and prevention through focus groups and surveys. In Specific Aim 2, we will construct a proof of concept smartphone app with targeted features for HIV prevention and health maintenance. In Specific Aim 3, we will test the proof of concept smartphone app within the target population. These aims will demonstrate the feasibility and acceptance of a novel smartphone mobile app for effective, remote HIV prevention and care for urban YMSM. Environment: CTIS has excellent experience developing mobile technology solutions for healthcare applications. Our partner and subcontractor in this grant application, JI, works closely with the YMSM community at Baltimore providing HIV care, prevention, and outreach services. Collectively we bring together all the capabilities required to successfully execute the Phase I feasibility study.